Research and analysis

Common animal-associated infections (England): second quarter 2023

Updated 29 February 2024

Applies to England

Background

This quarterly report is produced by the Emerging Infections and Zoonoses team in the Clinical and Emerging Infections Directorate, UK Health Security Agency (UKHSA). As of 2023, the data presented in these reports is for England only. Data for Wales will be reported separately by Public Health Wales. Previous reports, presenting data for both England and Wales, can be found on the GOV.UK website.

The report summarises laboratory-confirmed (and probable for leptospirosis) cases of selected zoonoses reported in England between April and June 2023 (second quarter) and includes additional information on the quarterly trends for hepatitis E, leptospirosis, Lyme disease and toxoplasmosis.

It is important to note that not all cases will present to healthcare services, and cases may be treated empirically based on clinical suspicion without a confirmatory test. Therefore, the numbers in this report are expected to be an underestimate of the true burden of zoonotic disease in England, likely biasing towards severe infections as individuals with severe or symptomatic disease may be more likely to be tested. Furthermore, not all zoonoses presented in this report are notifiable in England. As such, it is likely not all confirmed laboratory test results are reported to UKHSA. For a list of notifiable diseases and causative organisms in England please see the Notifiable diseases and causative organisms: how to report webpage.

The impacts of the public health measures implemented in England due to the COVID-19 pandemic during 2020 and 2021 should be considered when making comparisons with this time period.

Data reported as provisional is subject to change due to late notifications and de-duplication.

The data presented in this report supersedes data in previous reports due to late notifications and de-duplication.

Overview

Table 1. Animal-associated infections in England: quarterly confirmed laboratory reports by specimen date, Q1 2021 to Q2 2023

Disease (organism)	Q1 2021	Q2 2021	Q3 2021	Q4 2021	Total (2021)	Q1 2022	Q2 2022	Q3 2022	Q4 2022	Total (2022)	Q1 2023	Q2 2023*	Total (2023*)
Anthrax (Bacillus anthracis)	0	0	0	0	0	0	0	0	0	0	0	0	0
Brucellosis (Brucella spp.)	1	2	3	1	7	1	3	4	5	13	2	7	9
Hepatitis E	348	349	274	300	1,271	322	394	343	455	1,514	377	338	715
Leptospirosis (Leptospira spp.)	7	5	16	26	54	4	10	26	12	52	5	8	13
Lyme disease (Borrelia burgdorferi)
All cases	118	220	565	230	1,133	139	233	549	247	1,168	152	209	361
Acute infections	58	142	471	173	844	89	187	419	169	864	83	147	230
Pasteurellosis (Pasteurella spp.)	161	214	196	145	716	173	214	230	184	801	151	222	373
Psittacosis (C. psittaci / C. abortus)	2	1	1	1	5	0	0	0	0	0	4	0	4
Q-fever (Coxiella burnetii)†
All cases	3	2	5	2	12	6	4	9	8	27	3	8	11
Acute infections	2	2	5	2	11	4	2	6	6	18	3	5	8
Toxoplasmosis (Toxoplasma gondii)**	46	50	39	52	187	54	37	57	45	193	63	54	117

*Provisional data.

† Numbers for 2021 and 2022, published in the previous report, have been corrected following an internal review.

**Based on date specimen received.

Hepatitis E

The national hepatitis E virus (HEV) surveillance reports reference laboratory data (Public Health Laboratory Birmingham and the Blood Borne Virus Unit Colindale) together with additional cases reported by local laboratories through the Second Generation Surveillance System (SGSS). The combined data sets provide a more accurate reflection of the number of acute HEV infected cases reported in England.

There were 338 laboratory-reported cases of HEV infection in the second quarter of 2023. This is a decrease compared to 394 cases reported in the same quarter of 2022. Figure 1 shows the number of HEV infections by quarter between 2019 and 2023. The data shows an increase in cases between the third quarter of 2021 and the fourth quarter of 2022, and a decline in the first half of 2023.

Figure 1. Laboratory confirmed cases of hepatitis E in England by quarter, Q1 2019 to Q2 2023

Of the cases reported in the second quarter of 2023, 196 (58.2%) were male (aged 13 to 89 years, median 58 years) and 141 (41.8%) were female (aged 11 to 93 years, median 57 years). One person was of unknown sex (Table 2). The persisting observation of the predominance of older men (aged 45 years and over) remains unexplained.

Table 2. Laboratory confirmed cases of hepatitis E in England by age group and sex, Q2 2023

Age group (years)	Male	Female	Unknown	Total
0 to 14	11	6	0	17
15 to 24	47	35	0	82
25 to 44	78	53	1	132
45 to 64	1	2	0	3
Over 64	59	45	0	104
Total	196	141	1	338

Leptospirosis

Data for leptospirosis was obtained from the Rare and Imported Pathogens Laboratory (RIPL, UKHSA Porton). As of 1 August 2020, a laboratory confirmed case of leptospirosis is defined by a positive 16S rRNA PCR result only. An Immunoglobulin M (IgM) enzyme-linked immunoabsorbent assay (EIA) continues to be performed on all samples of suspected leptospirosis cases. A case with a positive leptospirosis IgM result will usually be treated clinically on the basis of this result, even in the absence of a positive PCR result. A case with a positive IgM but without a confirmatory PCR result is therefore reported as a probable case for surveillance purposes. National surveillance of probable cases of leptospirosis was introduced in 2021.

There were 8 confirmed cases and 26 probable cases of leptospirosis reported cases in the second quarter of 2023, compared to 10 confirmed and 20 probable cases reported in the same quarter of 2022. Figure 2 shows the number of confirmed cases reported by quarter over the past 5 years (2019 to 2023).

Figure 2. Laboratory confirmed cases of leptospirosis in England by quarter, Q1 2019 to Q2 2023

In the second quarter of 2023, all confirmed cases (n=8, 100%) were male (aged 22 to 59 years). Cases were reported in the South East (2), the South West (2), the East Midlands (1), the East of England (1), London (1) and Yorkshire and Humber (1).

Of the confirmed cases cases, 2 reported recent travel abroad, both to southeast Asia. Country of recent travel does not necessarily reflect where the infection was acquired. Of the 8 confirmed cases, 2 reported potential exposures, both of which had an exposure linked to a water source – 1 case reported swimming and kayaking, and 1 case reported white water rafting.

Lyme disease

Data for Lyme disease was obtained from the Rare and Imported Pathogens Laboratory (RIPL, UKHSA Porton). The total number of confirmed Lyme disease cases reported in the second quarter of 2023 (n=209) was lower than in the same time period in 2022 (n=233). The total number of acute cases reported was lower in the second quarter of 2023 (n=147) compared to to the same period in 2022 (n=187). It should be noted that diagnosis for acute Lyme disease presenting with erythema migrans (“bullseye rash”) is made clinically and testing is not recommended, as per NICE guidelines. The number of laboratory-confirmed cases presented in this report are therefore likely an underestimate of the true burden of acute Lyme disease.

Figure 3 shows how the number of cases continues to peak during the summer months (third quarter), which corresponds to the peak period of exposure to ticks in the UK – the spring and summer months.

Figure 3. Laboratory confirmed cases of Lyme disease in England by quarter, Q1 2019 to Q2 2023

Of the total cases reported in the second quarter, 147 (70.3%) were acute (including 20 with neurological Lyme disease) and 62 (29.7%) were longstanding. Of the acute cases, 72 were male (aged 2 to 84 years, median 51) and 75 were female (aged 5 to 85, median 46 years). Table 3 shows the age group and sex distribution.

Table 3. Laboratory confirmed acute cases of Lyme disease in England by age group and sex, Q2 2023

Age group (years)	Male	Female	Total
0 to 14	9	6	15
15 to 24	2	7	9
25 to 34	7	13	20
35 to 44	14	11	25
45 to 54	15	10	25
55 to 64	12	16	28
65 to 74	8	9	17
Over 75	5	3	8
Total	72	75	147

The regions that reported the most acute cases in the second quarter of 2023 were the South West (n=48), the South East (n=44) and London (n=29) (Table 4). This data is based on the location of the referring hospital or laboratory and does not necessarily reflect the geographic area where the tick bite occurred. Four of the acute cases in the second quarter of 2023 reported foreign travel, specifically to North America (n=1), Southern Africa (n=1), Western Europe (n=1) and the Caribbean (n=1).

Table 4. Laboratory confirmed acute cases of Lyme disease in England by region, Q1 2022 to Q2 2023

UKHSA Centre	Q1 2022	Q2 2022	Q3 2022	Q4 2022	Total 2022	Q1 2023	Q2 2023	Total 2023
East Midlands	4	1	1	3	9	1	0	1
East of England	4	12	23	15	54	2	5	7
London	22	31	69	38	160	18	29	47
North East	2	2	16	7	27	4	2	6
North West	12	20	28	14	74	12	10	22
South East	18	59	132	42	251	23	44	67
South West	16	54	106	35	211	16	48	64
West Midlands	6	0	22	2	30	3	4	7
Yorkshire and Humber	5	8	21	12	46	4	5	9
Total	89	187	418	168	862	83	147	230

Toxoplasmosis

Data for toxoplasmosis in England was obtained from the Toxoplasma Reference Unit (TRU, Public Health Wales Swansea). There were a total of 54 confirmed toxoplasmosis cases reported in the second quarter of 2023, an increase compared to 37 in the same quarter of 2022.

Figure 4. Laboratory confirmed cases of toxoplasmosis in England by quarter, Q1 2019 to Q2 2023

Of the total confirmed cases, 16 (29.6%) were male (aged 16 to 81, median 35.5 years) and 38 (70.4%) were female (aged 0 to 78, median 33 years). There was 1 case with unknown age. Table 5 shows the age group and sex distribution.

Table 5. Laboratory confirmed cases of toxoplasmosis in England by age group and sex, Q2 2023

Age group (years)	Male	Female	Total
Under 15	0	1	1
15 to 24	2	8	10
25 to 44	10	20	30
45 to 64	2	5	7
Over 64	2	3	5
Unknown	0	1	1
Total	16	38	54

Psittacosis

Data for psittacosis was obtained from the Respiratory and Vaccine Preventable Bacteria Reference Unit (RVPBRU) in Colindale and from cases reported by local laboratories through the Second Generation Surveillance System (SGSS). It is recognised that it is difficult to diagnose infection retrospectively through serological assays and, as such, following an external review, the surveillance case definitions for psittacosis were reviewed. As of 1 January 2023, a confirmed case of psittacosis is defined by a positive 16S rRNA PCR result or culture isolation only. This case definition has been applied to all retrospective data presented in these reports from 2023.

It should be noted that the existing PCR assay is unable to differentiate between Chlamydia psittaci (C. psittaci) and Chlamydia abortus (C. abortus). However, as there are currently no other reliable methods of psittacosis identification, the numbers presented in these reports will reflect laboratory confirmed cases with a positive PCR result for C. psittaci / C. abortus.

There were no reports of psittacosis in the second quarter of 2023. There were also no reports in the same quarter of 2022. Figure 5 shows the number of laboratory confirmed cases of psittacosis between 2019 and 2023.

Figure 5. Laboratory confirmed cases of psittacosis in England by quarter, Q1 2019 to Q2 2023

Other zoonotic organisms

There were 20 reports of Capnocytophaga spp. infection in the first quarter of 2023. This is similar to the number reported in the same quarter of 2022 (n=18). Of the cases reported this quarter, 14 were further speciated to C. canimorsus. Of those speciated, 6 were male and 8 were female, and cases were reported in the South East (5), the South West (4), the East Midlands (2), North East (1) and Yorkshire and Humber (1). Capnocytophaga spp. are frequently carried in the mouths of companion animals (cats and dogs) or humans, and may be associated with an animal or human bite or opportunistic infections in those with impaired immune systems.

There were 7 reports of Mycobacterium marinum infection in the second quarter of 2023. This is the same as the number reported in the same quarter in 2022 (n=7). All cases reported this quarter were male.

There were no reports of Erysipelothrix rhusiopathiae in the second quarter of 2023; there were also no reports in the same quarter of 2022.

There was 1 case of toxigenic Corynebacterium ulcerans infection reported in the second quarter of 2023 – in a female aged over 50 years who reported contact with companion animals. This is the same as the number of cases reported in the same quarter of 2022 (n=1). In England, contact with companion animals remains the most frequently reported exposure for individuals with confirmed toxigenic C. ulcerans infections. However, the animals may not show evidence of infection and it is not always possible to confirm the carriage of C. ulcerans in animals.

There were 9 reports of Taeniasis in the second quarter of 2023. This is an increase compared to 5 cases reported in the same quarter of 2022. Of the cases reported this quarter, 3 were further speciated to T. saginata.

There was 1 report of Toxocariasis in the second quarter of 2023. There were no reports in the same quarter of 2022.